1. Field of the Invention
The present invention relates to a film information reading device of a camera, and more particularly, to such a device capable of reading out film information such as the film sensitive speed or number of frames, when the camera is loaded with a film cartridge having on its outer surface a code pattern representing this information.
2. Description of the Related Art
A roll film cartridge having on the outer periphery thereof a code pattern consisting of a plurality of conductive or insulated code areas representing film information, has been recently developed and proposed together with a camera adaptable to use such a film cartridge. FIGS. 1A and 1B illustrate a film cartridge having a code pattern consisting of twelve code areas 1a, through which film information such as the film sensitivity, number of frames, and allowable exposure limit (i.e. exposure range), are automatically transmitted to an electrical circuit in the camera. In order to read this film information through the code pattern, a reading device must be provided in a film cartridge chamber of the camera in such a manner that the code pattern is in contact with the reading device when the film cartridge 1 is loaded into the camera. The film cartridge 1 has upper and lower cover caps 1b having a larger diameter than the outer peripheral surface on which the code pattern is formed. Therefore, electrical contacts of the reading device in the camera must be inwardly projected from the inner wall of the film chamber by at least a difference (h), as shown in FIG. 1B.
On the other hand, as shown in FIG. 2, the film cartridge chamber 12 of a camera is provided with a film rewind fork 13, which is projected into the film chamber in such a manner that it engages with a key formed at a shaft end of the film cartridge when the film cartridge is loaded into the camera. In many cameras, the film rewind fork 13 is designed to retract upwardly into the camera body so as not to interfere with the loading or unloading of the film cartridge. However, in some cameras, the rewind fork 13 is designed not to retract upwardly, because the space of the camera body is used for other purposes. For example, in many cameras having an automatic film rewinding mechanism, the rewinding fork 13 is usually designed not to retract. In these cameras, the film cartridge must be loaded by inserting it in the axial direction thereof. Consequently, the cartridge is inserted obliquely in the direction indicated by A in FIG. 2 from a position below and slightly behind the film chamber 12.
Providing these cameras with the above-mentioned film information reading device will give rise to a problem wherein, when the film cartridge is obliquely inserted, the cap edge thereof may interfere with the electrical contacts of the code reading device, since they are projected as mentioned above, and the film cartridge loading may not proceed smoothly. To obviate this problem, it is suggested to provide movable electrical contacts which retract when the edge of film cartridge comes into contact therewith. However, this is not sufficient to completely obviate the above-mentioned problem, since this solution is possible only when the amount of the projection of the electrical contacts is very small, since otherwise the edge of the film cartridge would laterally come into contact with the contacts, and therefore, the contacts could not retract. In fact, the electrical contacts must project for 1.5 mm to 2.0 mm to attain a reliable electrical connection. However, the above-mentioned interference with the contacts cannot be prevented with this amount of projection.
U.S. Pat. Nos. 4,024,557 and 4,074,286 disclose a system for reading film information such as film speed, represented by a code pattern provided on a film cartridge, through electrical contacts in a camera body. U.S. Pat. Nos. 4,200,371 and 4,431,283 further disclose pivotable contact members which come into contact with a code pattern on a film cartridge when the cartridge is loaded or a film chamber is closed with a back cover.